Banksia Sessilis - Distribution and Habitat

Distribution and Habitat

Banksia sessilis is endemic to the Southwest Botanical Province, a floristic province renowned as a biodiversity hotspot, located in the southwest corner of Western Australia. This area has a Mediterranean climate, with wet winters and hot, dry summers. B. sessilis occurs throughout much of the province, ranging from Kalbarri in the north, south to Cape Leeuwin, east along the south coast as far as Bremer Bay, and inland to Wongan Hills and Kulin. It thus spans a wide range of climates, occurring in all but the semi-arid areas well inland. It is also absent from the Karri forest in the cool, wet, southwest corner of the province, but even there, B. sessilis var. cordata occurs along the coast.

The species tolerates a range of soils, requiring only that its soil be well-drained. Like most dryandras, it grows well in lateritic soils and gravels, although this species is also found in deep sand, sand over laterite, and sand over limestone. It also occurs in a range of vegetation complexes, including coastal and kwongan heath, tall shrubland, woodland and open forest. It is a common understorey plant in drier areas of Jarrah forest, and forms thickets on limestone soils of the Swan Coastal Plain. Banksia sessilis sets a large amount of seed and is an aggressive coloniser of disturbed and open areas; for example, it has been recorded colonising gravel pits in the Darling Scarp.

Nothing is known of the conditions that affect its distribution, as its biogeography is as yet unstudied. An assessment of the potential impact of climate change on this species found that its range is likely to contract by half in the face of severe change, but unlikely to change much under less severe scenarios.